This invention relates to an improved leak detector and, in particular, to a leak detector that utilizes electromagnetic signals to accurately discern the unwanted escape of a fluid (gas) from a hermetically sealed unit. More specifically, the present invention involves a highly sensitive leak detector that is able to sense the present of minute leaks in a relatively short period of time.
Some leak detectors that are presently in use rely upon a pressure decay principle to discern leaks in hermetically sealed units. Initially, the unit is pressurized using air or some type of gas to a relatively high test pressure. The pressure within the unit is then monitored over a period of time. In the event of a leak, a decrease in the unit pressure will be sensed provided it is within the sensitivity range of the test equipment. Ordinarily, this type of equipment will not be able to detect leaks below 5 cc/min. even when utilizing test pressures of about 300 psi.
Another type of leak detector relies upon a flow monitor to discern the loss of fluid from sealed test units. Here again, a gas or liquid under relatively high pressure is initially brought into the test unit. If a leak is present, more fluid must be supplied to the unit to maintain equilibrium conditions. A flow sensor is provided in the fluid supply line that will detect the flow of make-up fluid into the unit. The detecting system, however, is only as sensitive as the flow sensor and, as a consequence, relatively small leaks can not generally be detected, particularly at low test pressures.